In 2010 the Amazon Basin experienced unusually dry conditions, a second major drought in 5 years, a pattern which is remarkably similar to some predictions of the future climate of the region. This is because most climate models predict an increase in dry season intensity, and all an increase in temperature in the coming century as a consequence of global climate change. Whether or not long-term climate change is already involved the current event can help us evaluate how humid forest, deciduous forests and savanna ecosystems and species respond to drying, so helping assess the potential scale of impacts as the Amazon climate dries. Our team has a large network of on-the-ground sample plots in the region, and because these are standardised they represent an excellent opportunity to measure the actual impacts of drought. We already did this with the severe 2005 drought (described then as 'the drought of the century' but surpassed in extent this year). In this proposal we focus on our sites at the southern fringes of Amazonia, an area very strongly affected by the 2010 drought. This large area is a 'zone of tension' between Amazon moist forest species, deciduous species, and savanna, with the various vegetation types sometimes adjacent in the same sites. Here we have 30 permanent plots available so we are able for the first time to measure the on-the-ground impacts on different species and vegetation formations at this forest/savanna mixing zone. This is important because it is expected that within these zones of ecological tension that long-term vegetation changes will first be observed, and these areas of high diversity and high carbon storage could significantly affect regional carbon emissions. We plan to do the following: 1) Recensus 30 southern Amazon plots to record tree growth and vegetation productivity. 2) Remeasure nearly 500 trees where we have pre-drought measures of details of their structure, to assess if drought has changed them. 3) Install high-precision measurement tools ("dendrometers") on trees of key species, to enable better monitoring of future droughts 4) Analyse data collected from (1) & (2) to test our hypotheses: 1. The 2010 drought caused biomass carbon loss from forest but not savanna. We expect savanna to prove more resilient than forest, and for forest responses to mirror those of 2005. 2. The 2010 drought accelerated tree death and reduced growth in the forest but not the savanna. We expect forest species to be more sensitive than savanna species when faced with the same degree of drying. 3. Forest & savanna plots that had the greatest biomass loss and/or mortality are those with shallowest soils. We expect soil depth to affect the drought response, with shallower soils having fewer moisture reserves. 4. Within each stand, species which also occur in drier areas were more drought-resistant than those already at the dry end of their range. We expect that the risk a tree faces from drought is related to its geographic distribution, so that species that are typically found in moister climates will be more drought-sensitive than their neighbours. 5. Species differences in drought sensitivity are related to variation in structural traits. We expect the more drought-resistant evergreen trees will have a more conservative hydraulic structure, such as denser wood. The expected outcomes of this research are: 1) Improved quantification of the sensitivity of transitional Amazon forest to drought. 2) A first assessment of the differential sensitivity of forest and savanna trees to drought conditions. 3) By integrating (1) & (2), understand better the chances of savanna replacing forest in the "zone of tension", and even into core Amazon forests, as the climate dries. 4) Improved understanding of the physiological basis of drought-resistance and the importance of soil conditions. 5) The infrastructure installed to allow local collaborators to evaluate effects during future droughts.

The dynamics of past human-environment relationships is one of the most relevant issues in archaeology today. Pre-Columbian (pre-1492) Amazonia provides a case study of a long-standing debate into human-environment interactions. At one end of the spectrum are those who view Amazonia as a largely pristine wilderness which has shaped human history, while at the other are those who argue that Amazonia has been utterly transformed into a domesticated landscape by millennia of human land use. Recent ground-breaking discoveries of vast, pre-Columbian landscape engineering projects -- monumental habitation mounds, ring ditches, causeways and canals -- overturn the paradigm that environmental constraints limited cultural development in Amazonia to simple semi-nomadic, hunter-gatherer lifestyles, as practiced by indigenous peoples today. However, the processes by which these complex (stratified) societies emerged and declined, and their relationships with the environment, remain unresolved. This uncertainty stems from a paucity of archaeological data and a lack of the inter-disciplinary collaboration essential for investigation of human-environment interactions. This project therefore assembles an international, multi-disciplinary research team to integrate archaeological and environmental approaches and data to address our overarching research aim: To determine the relationships between the emergence and demise of stratified societies, food procurement strategies, and environmental conditions in Pre-Columbian Amazonia. We focus on three study areas in SW Amazonia which provide a unique opportunity to examine the emergence and demise of different societies across a broad spectrum of environmental conditions -- in terms of forest cover, soil quality, and flood/drought risk. The following techniques will be employed: 1. Archaeological excavations will reveal human occupation histories spanning over 8,000 years, while laboratory-based analyses of pottery, human bones, and soils will provide insights into diet, food processing, cultural practices, and land use. 2. Microscopic analyses of ancient charcoal, pollen, and plant remains from nearby lake/channel sediments and soils will reveal forest and savanna resource management; e.g. use of fire and selection of economically important species such as fruit trees and palms. 3. The evolutionary history of the physical landscape and river networks will be reconstructed to determine how changes in flood regime influenced occupation history and land use. 4. The above data will be compared with annual-resolution climate records from nearby cave stalagmites to determine potential linkages between cultural/land-use change and climate change. 5. To integrate these different lines of evidence, and understand their relationships through time, it is essential to have secure chronologies, which we will achieve predominantly through radiocarbon dating. There is increasing interest in cultural heritage and identity among present-day urban and rural Amazonian communities. We will therefore engage with a museum in Trinidad (the provincial capital of one of our Bolivian study areas) to improve its educational value by incorporating best practice to develop stimulating, interactive museum exhibits and accompanying booklets that can convey our project findings to a wide public audience. We will also explore the potential for building eco-museums in rural villages in the heart of our archaeological study areas. By engaging with urban and rural communities in this way, we hope to lay the foundation for longer-term impact by contributing to the wider socio-political issue of land-use conflict between indigenous peoples, landowners, and conservationists. Broader, international impact will be achieved via our project website and end-of-project exhibitions in museums of the major Bolivian and Brazilian cities of La Paz and Sao Paulo.

The overall aim of this project is to determine and communicate the risk of significant change to the Amazon rainforest caused by anthropogenic disturbance and climate change. We will address a fundamental issue of our time, on the likelihood of Amazon rainforest dieback in the 21st century and identify regions that are most susceptible. We will combine this new knowledge with policies and scenarios developed by key stakeholders to co-design a Safe-Operating-Space for Amazonia. To address the iconic issue of Amazon dieback we will advance new ecological understanding of how forests grow, decline and recover following disturbance from climate extremes, forest fire and deforestation and their interaction in the context of 21st Century global warming. We will build novel datasets using a new forest plot network, drones and satellites to produce near-real-time maps of the risk to forests from climate, and track individual large-tree mortality across the basin. Together this information will be used in mathematical models to help estimate the risk of future forest dieback. We will join this work with models used to predict the effects of land use (forest conversion, degradation) on forest function, and the ecosystem services these forests provide to humanity. The outputs will enable us to deliver new information to policy makers regarding future options for land use, helping them to build optimal land use pathways that minimise the risks that may arise out of large-scale forest loss or dysfunction in Amazonia. The Amazon forest plays a vital role in the world's climate. In addition, by annually absorbing 5-10% of human-related CO2 emissions via vegetation growth, the region acts as a large brake on climate change. Climate extremes (eg drought), forest fires and deforestation reverse this process, causing net emissions to the atmosphere. If this were to happen on a large enough scale, via increased forest loss or increased rates of climate change - or their interaction - the resulting positive effect on global CO2 and climate change, would make the already-challenging Paris climate targets virtually impossible. In short, climate change, forest fires and deforestation have been identified as major intensifying and interacting threats to Amazonia. A substantive loss of Amazonian forest, also known as "Amazon dieback", would have huge negative consequences for human well-being, biodiversity, biogeochemical cycling, and regional and global climate. However, the level of global climate change combined with human disturbance that could trigger large-scale dieback is not known. Climate change is predicted to become more intense in the region alongside increases in human-driven deforestation and forest degradation (e.g fires, logging). Their impacts are poorly understood because of a lack of data, and because models cannot currently represent the key processes well enough. We have gathered leading UK and S American scientists in the fields of ecology, ecophysiology, Earth observation (using satellites) and the mathematical modelling of vegetation growth, land-use and climate as applied to Amazonia. We are uniquely positioned to make a step-change in understanding the combined effects of climate stress and human disturbance on Amazonia. Our measurements will build new knowledge about intact and disturbed forests, their stability and the physiology driving their stress responses. These knowledge advances will enable new modelling of forest-climate-land-use interactions which we will use to inform policymakers. We will engage with stakeholders from state to international levels to co-develop land-use scenarios that minimise risk in future climate and forest ecosystem services. Overall, we propose multiple large and integrated advances in empirical and modelling studies of the forests of Amazonia, and will build a science-policy dialogue that delivers significant impact locally, regionally and globally.